Table of Contents
Introduction to Tankless Water Heaters
This is a new technology for many people, but amazingly this technology has
been around for a long time. The products have been produced and improved for
several years resulting in the most efficient and cost effective way to heat water.
Radiant Heating vs. Domestic Use
Many people look into tankless water heaters for use with radiant heating systems.
A radiant heating system runs hot water through a radiator in a room or pipes
in a floor to effectively heat the house. Tankless water heaters are not designed
for this use. There are some units with modifications that can be used for this
purpose, but in most cases the safest implementation of a heater for a radiant
heating system is a boiler. If you plan on using a tankless water heater for a
radiant heating system you could void your warranty or destroy your heater far
earlier then the expected life of the unit. Please call us and ask if you have
questions concerning this, there may be some alternatives that we can consider.
What type of water heater?
Some people are limited to gas appliances because they do not have electricity.
Others prefer to use an all-electric unit so they do not need a gas supply.
Many of the newer units are using a mixture of gas and electricity. The heaters
are using the gas to heat the water, and the electricity for electronic spark
ignition, freeze protection, combustion air fan, and operating controls. As the
water heaters are advancing we are seeing more electronic components incorporated
in their design, such as sensors and fans, thus more units are requiring electricity.
What if I do not have electricity?
We have some gas tankless water heaters that run entirely on gas (both propane and natural gas) and
require no electricity. It is important to select the correct water heater, as many of them say gas, but
they still require electricity for the electric spark ignition and electrical components.
Gas Units (these units use gas exclusively, no electricity):
-Paloma
PH6 Gas Tankless Water Heater
-Paloma
PH12M Gas Tankless Water Heater
-Paloma
PH24M Gas Tankless Water Heater
-Takagi TK3 Residential
Gas Tankless Water Heater
I want a unit that runs entirely on electricity!
We have units that do run entirely on electricity. These are excellent water
heaters with a lot of technology built into them, but there is a very important
thing that you must remember when you want to run a heater completely off of electricity.
Can your current service handle it? An electric water heater must generate a lot
of heat to raise the temperature of the water as it passes by! This process uses
a lot of amperage. When you are picking out an electric water heater you should
check your total amperage of your electric service and see if you can accommodate
the additional amps required by a tankless electric water heater. For example,
if you have a 100 amp service and you are going to buy a 80 amp water heater,
then you will only leave yourself with 20 amps for the rest of the house, when
the water heater is on full. It is important that you know how much current the
rest of the house needs, and that you read the instruction manual about your water
heater so you know how much current that unit uses. Then you must ensure that
your electric service will be large enough to provide for all of the uses. The
electric units require dedicated lines from the breaker box all the way to the
heater, they often times use smaller gauge (larger wire) then is used in the rest
of the house. They also require their own breakers. Many people will run the units
on 240VAC instead of 120VAC. It is possible to install 3-phase units as well,
but this would be more for large scale installations or for commercial applications.
Most people think they have 3-phase running to their houses, but in reality it
is almost always single phase. Please call us or your electrician if you have
any questions about tankless electric water heaters.
Electric Models:
-Stiebel
Eltron DHC-E 8/10
-Stiebel
Eltron DHC
-Stiebel
Eltron Tempra 12
-Stiebel
Eltron Tempra 20
-Stiebel
Eltron Tempra 24
-Stiebel
Eltron Tempra 29
-Stiebel
Eltron Tempra 36
-EEMAX
"Single Point" & "Flow Control" Series
-EEMAX
"Thermostatic" Single Element Series
-EEMAX
Marine Electric Tankless Water Heater
-EEMAX
Series Three Residential Heater
-EEMAX
Series Two
-EEMAX
Three Phase Industrial Heater
Indoors vs. Outdoors
Outdoor tankless water heaters are convenient because they require no venting,
but many of us live in climates where the temperatures sometimes reach below freezing.
Many tankless water heaters say that they have freeze protection, and in-fact
most of them do. The problem comes with the piping, there is no freeze protection
installed on exposed pipes that feed an outdoor unit. Thus, if you are in an area
where you receive below freezing temperatures, then an outdoor model is generally
not for you.
Considerations for Outdoor Units:
Even though an outdoor model does not require the consideration of venting, it does require that
we pay attention to where the exhaust goes. On all outdoor gas models the exhaust could blow back into
the house if installed next to a window or a door. There are a lot of different clearances declared in
the manuals for each water heater. It is important that you read and adhere to all of the clearances specified
in the manual. It is also important that you follow any local codes that could apply to the installation.
Outdoor Models:
-Paloma
PH-28ROF Residential Outdoor Gas Tankless Water Heater
-Paloma
PH-20ROF Residential Outdoor Gas Tankless Water Heater
-Paloma
PH-28COF Commercial Outdoor Gas Tankless Water Heater
-Takagi TK3 Residential
Gas Tankless Water Heater
Considerations for Indoor Units:
Indoor gas units require proper venting of the exhaust gases. There are two
categories of indoor gas units, they are fan assisted and atmospheric. Fan assisted
tankless water heaters can be vented vertically through a roof or horizontally
through a wall. Atmospheric gas tankless water heaters allow only vertical venting
without after market equipment.
Atmospheric:
Naturally aspirated units use the oxygen in the air for the flame to burn
and the exhaust is emited from the dwelling via a vent flue. For these units you
can use general venting that is installed in most houses such as B-vent. It is
important that the venting size be correct. If you have a flue that feeds into
a common vent for all of your appliances then make sure that it is large enough
to accommodate the water heater and all other appliances.
Atmospheric Models:
-Paloma
PH6 Gas Tankless Water Heater
-Paloma
PH12M Gas Tankless Water Heater
-Paloma
PH24M Gas Tankless Water Heater
Fan Assisted:
Fan assisted unit's use the oxygen in the air for the flame to burn and the exhaust
is forced out using a fan. For these units you must use special venting specified
in each units manual. For almost all fan assisted units you must use a Category
III stainless steel that is sealed. This venting can get expensive if venting
over a large distance. It is strongly recommended that you try and terminate the
vent as soon as possible when using a fan assisted unit. Fan assisted models draw
larger amounts of oxygen from the air thus they require more air to opperate.
Some people install the unit in a closet or confined space, not giving the unit a lot of air. If you
wish to do an install in an area like this then you need a Direct Vent model. You do not need a Direct
Vent model if you can give the room that the water is installed in, 1 square inch of access to house hold
air for every 1,000 BTU, or 1 square inch of access to fresh (from outside) air for every 4,000BTU. For
example if you are looking at a 200,000 BTU unit and you have an open area to the rest of the house that
is 200 square inches, or you have an area open to the outside that is 50 square inches then you would
not need a Direct Vent model. If you had a 200,000 BTU unit installed in an area where house hold air
could only pass through a 100 square inch area to reach the water heater, then this would not be enough
(200 sq in would be), then you would need a Direct Vent model.
Fan Assisted Models:
-Paloma
PH-28RIFS Residential Indoor Gas Tankless Water Heater
-Paloma
PH-20RIFS Residential Indoor Gas Tankless Water Heater
-Paloma
PH-28CIFS Commercial Indoor Gas Tankless Water Heater
-Takagi
TK-2 Gas Tankless Water Heater
-Takagi
TK-Jr. Gas Tankless Water Heater (a conversion
kit is available to convert this unit to Direct Vent)
-Takagi
T-KD20 Gas Tankless Water Heater
-Takagi
T-M1 Gas Tankless Water Heater
-Takagi TK3 Residential Gas Tankless Water Heater
Direct Vent
Direct vent models use a venting system that circulates air from outside the home. The heater itself has
a sealed cover and does not use any air from the room where it is installed. Two pipes run from the water
heater through the roof or wall of the home, one for exhaust, one for fresh air intake. This is acheived
using either concentric piping (a pipe within a pipe) from the heater to the outside, or using two individual
pipes with a concentric pipe termination through the wall or roof depending on the model. Please click
here to see a diagram of a direct vent system.
Fan Assisted Direct Vent Models:
-Paloma
PH-28RDVS Residential Direct Vent Indoor Gas Tankless Water Heater
-Paloma
PH-20RDVS Residential Direct Vent Indoor Gas Tankless Water Heater
-Paloma
PH-28CDVS Commercial Direct Vent Gas Tankless Water Heater
-Takagi TK3 Residential Gas Tankless Water Heater
How big does the capacity of the water heater need to be?
Tankless water heaters are classified by their rated input expressed in BTU/hour.
BTU stands for British Thermal Units which is a way of measuring energy. The higher
the BTU rating the more water the water heater can heat, or the hotter it can
get the water. The best place to start understanding how to gauge the "capacity"
of a tankless water heater is by the units in which it is measured. A tankless
water heater is said to raise the temperature of water a certain amount of degrees
per flow rate. For example the Paloma PH-28RIFS can raise the temperature of the
water 45ºF at 7.4gpm.
The 7.4gpm means a flow rate of 7.4 gallons per minute. To put this in perspective,
a sink uses about 1gpm, and a shower about 2.5gpm. If we want the water in our
house to get to 120ºF so it will be really hot for the dishes and laundry, and
we know that we have 50ºF ground water coming into the house, then we know that
we need a 70ºF rise in the temperature of the water (120ºF - 50ºF). From looking
at the information on the PH-28RIFS web page we see that there is a 4.8gpm flow
rate at a 70ºF rise, well that is what we want is a 70ºF rise. In order to maintain
the water temperature through out the house we should not exceed a flow rate of
4.8gpm approximately 2 showers. If we want to use more the 4.8gpm (2 showers)
and keep the temperature at 120ºF then we need to look at different units, or
the possibility of putting multiple units together.
When we say raise the temperature of water 45º we mean raise the temperature
of the water 45º above what it is coming in at. Because we are raising the temperature
of the water it is very important that we consider the temperature of the ground
water when it comes into our home. Let's say that we are using the PH-28RIFS,
at 7.4gpm. This means we have the equivalent of 3 showers going at this exact
point in time. At this flow rate (7.4gpm) we can get a 45ºF rise in the temperature
of the water. If we live in California and the ground water temperature is pretty
warm at about 65ºF, then the water can get up to 110ºF (45ºF + 65ºF). However
if we are in Colorado and the ground water is about 45ºF then the water will only
get up to 90ºF (45ºF + 45ºF). If we want the water hotter at this 7.4gpm flow
rate then we can look at different units, or the possibility of putting multiple
units together.
High Volume Models (6gpm and above @ 45º rise):
-suggested unit #1
-suggested unit #2
Medium Volume Models (5-6.9gpm @ 45º rise):
-suggested unit #1
-suggested unit #2
Low Volume Models (up to 4.9gpm @ 45º rise):
-suggested unit #1
-suggested unit #2
Commercial vs. Residential
As always commercial in water heaters means the ability to heat more water,
or to heat the water to higher temperatures. The residential models that we sell
are plenty for a typical home, and if you have a high use home then we have some
new interesting residential solutions for you!
Commercial Capabilities:
Our commercial units are in performance and efficiency the same as our residential units. The biggest
difference between a commercial unit and a residential unit is the ability connects several units together.
With the commercial units and a manifold you can connect up to 20 units together to achieve a 4,000,000BTU
system. The manifold will control the amount of units that are firing to deliver the correct temperature
water. The manifold also alternates the firing order so that one unit is not always getting used and others
never getting used. It really helps to level out maintenance and to decrease unnecessary wear on one unit.
Another feature of the commercial units is there ability to raise temperature to 140ºF for commercial/industrial
applications.
Commercial Models:
-Paloma
PH-28CIFS Commercial Indoor Gas Tankless Water Heater
-Paloma
PH-28COF Commercial Outdoor Gas Tankless Water Heater
-Paloma
PH-28CDVS Commercial Direct Vent Gas Tankless Water Heater
-Takagi
T-M1 Gas Tankless Water Heater
-Takagi TK3 Residential
Gas Tankless Water Heater
Residential Capabilities:
Our residential models provide the typical water heater capabilities and capacities for average homes.
Some times people use more then some of our largest residential models can supply, so Paloma is coming
out with DUOnex™ technology which allows two of their residential units to be linked and provide twice
the power of a single unit. This is a simple cable that will plug directly into both units. Unfortunately
the DUOnex™ has not been released yet. The residential units in general will allow you to set the temperature
of the water. Many water heaters will only allow you to set the out coming water temperature if you have
a remote, and only certain models come with remotes. If you would like the remote functionality then watch
for the units that use remotes and have them included with the water heaters. The remotes also provide
a must have feature for technical issues, they give diagnostic codes which explain what is wrong with
the water heater(s).
Residential Models:
(Remotes Included)
-Paloma
PH-28RIFS Residential Indoor Gas Tankless Water Heater
-Paloma
PH-20RIFS Residential Indoor Gas Tankless Water Heater
-Paloma
PH-28ROF Residential Outdoor Gas Tankless Water Heater
-Paloma
PH-20ROF Residential Outdoor Gas Tankless Water Heater
-Paloma
PH-28RDVS Residential Direct Vent Indoor Gas Tankless Water Heater
-Paloma
PH-20RDVS Residential Direct Vent Indoor Gas Tankless Water Heater
(Remotes Not Included)
-Takagi
TK-2 Gas Tankless Water Heater (Remote
available)
-Takagi
TK-Jr. Gas Tankless Water Heater
(Remote
available)
-Takagi
T-KD20 Gas Tankless Water Heater
(Remote
available)
-Takagi
T-M1 Gas Tankless Water Heater
(Remote
available)
-Takagi TK3 Residential
Gas Tankless Water Heater (Remote available)
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